Due to the decline of birth rates and improvements of the medical environments, the percentage of the elderly population in a great number of countries has risen significantly, and so has the prevalence of chronic diseases. As a result, the need for medical care services increases continuously. With the development of such services, techniques for monitoring a person's body movements at home have evolved so much that a medical care service provider can now obtain real-time and comprehensive information about the activities and states (e.g., breathing, body movements, the gravity center of the body, and body postures) of a monitored person (e.g., an elderly person or one with a chronic disease) in order to provide the person with the necessary medical care services rapidly and proactively.
Today, a sensing device as shown in FIG. 1 is commercially available for a medical care service provider to keep track of a monitored person's various activities at home (e.g., when and how the person gets on or off the bed, sleeps, moves, and is seated). Referring to FIG. 1, the sensing device 1 includes two layers of elastic structures 11, a plurality of first conductive fibers 12 (e.g., conductive metal fibers, conductive metal compound fibers, or conductive carbon black fibers), and a conductive fabric 13. The first conductive fibers 12 are sewn on the elastic structures 11 and exposed on their opposing sides respectively. The conductive fabric 13 is woven from second conductive fibers 131 and a common yarn 132 (or from a mixed yarn spun from the second conductive fibers 131 and common fibers) and is provided between the elastic structures 11. When the sensing device 1 is compressed by an external force, the elastic structures 11 are compressed and deformed such that the first conductive fibers 12 contact with and are electrically connected to the second conductive fibers 131 in the conductive fabric 13, forming a plurality of contact points and a plurality of sensing resistors. A control module (not shown) electrically connected to the first conductive fibers 12 or the conductive fabric 13 of the sensing device 1 can generate signals according to the relationships between the total resistance of the sensing resistors, the operating voltage of the control module, the magnitude and area of the pressure applied to the sensing device 1, and the number of the contact points. By connecting the control module to another electronic device (not shown) in a wired manner or wirelessly, a medical care service provider can process and analyze the signals by way of the electronic device and thus be informed of the monitored person's activities.
The sensing device 1 is applicable to various products in a home environment (e.g., mattresses, seat cushions, table and chair leg cushions, and even clothes) to enable monitoring of a monitored person's activities at home, and thanks to its non-invasiveness and low constraint, the sensing device 1 can effectively reduce the monitored person's psychological resistance. In addition, the sensing device 1 has such advantages as lightweight, structural simplicity, pliability, ease of use, and high comfort. Hence, in the field of home medical care services, the sensing device 1 has gradually become an important technique for use by a variety of monitoring apparatuses.
The inventor of the present invention has long been engaged in research and development related to medical care, paying close attention to market reactions and analyzing user feedbacks carefully. In the process, the inventor has found that, despite the foregoing advantages, the design of the sensing device 1 still has room for improvement. Referring back to FIG. 1, the conductive fabric 13, which is woven from the second conductive fibers 131 (e.g., conductive metal fibers or conductive metal compound fibers) and the common yarn 132, may form a projecting pointed portion 131a after repeated bending. As the pointed portion 131a rises above the plane where the conductive fabric 13 lies, it is very likely that the pointed portion 131a will contact with the first conductive fibers 12 even if the sensing device 1 is not subjected to an external force. Should that happen, the first conductive fibers 12 will be electrically connected to the conductive fabric 13, causing erroneous electrical connection signals. Further, with the conductive fabric 13 being woven from the second conductive fibers 131 (e.g., conductive metal fibers or conductive metal compound fibers) and the common yarn 132, friction between the conductive fabric 13 and the elastic structures 11 may cause the common yarn 132 to produce lint balls 132a on the surface of the conductive fabric 13 after long-term use. The lint balls 132a may correspond in position to the first conductive fibers 12 and, due to the fact that the lint balls 132a are formed by the non-conductive common yarn 132, may hinder electrical connection between the first conductive fibers 12 and the second conductive fibers 131 when the sensing device 1 is compressed by an external force, thereby rendering the sensing device 1 less sensitive in use.
According to the above, although the conventional sensing device 1 can effectively reduce a monitored person's psychological resistance and advantageously provide convenient and comfortable use, the material properties of the conductive fabric 13 tend to lower the accuracy and sensitivity of detection signals after the sensing device 1 is used for some time, thus leaving something to be desired in terms of durability. Therefore, the issue to be addressed by the present invention is to modify the structural design of the sensing device 1, with the intention of increasing the accuracy and sensitivity of the detection signals of the sensing device 1.